Author

ORCID ID

Date Awarded

Document Type

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

John E Graves

Committee Member

Deborah K Steinberg

Committee Member

Ronald J Salz

Committee Member

Robert L Hicks

Abstract

Atlantic bluefin tuna (Thunnus thynnus) are targeted by recreational anglers along the east coast of the United States, and the fishery is thought to be of considerable economic value. However, limited knowledge of the preferences and values of fishery participants impedes the ability of managers to maximize fishery benefits and predict harvest patterns, while an incomplete understanding of post-release mortality hinders efforts to estimate total mortality resulting from the fishery. This dissertation used a multidisciplinary approach that relied heavily on cooperative research with the recreational fishing community to examine these questions. A stated choice survey of private anglers permitted to target bluefin tuna (Chapter II) estimated a fishery consumer surplus of over $14 million in 2015 while revealing striking heterogeneity in angler preferences. Respondents placed a high value on harvesting bluefin tuna, but about half of anglers also valued non-consumptive aspects of bluefin tuna fishing such as catch-and-release. Preference segmentation was largely driven by income and recent bluefin tuna targeting behavior, with high-income anglers who had recently targeted bluefin tuna more likely to belong to the non-consumptive group. These results indicate that liberalization of harvest regulations could result in significant, non-linear increases in effort and harvest should consumptive-oriented anglers decide to re-enter the fishery. A second survey, of Atlantic bluefin tuna fishermen who possess a permit enabling them to fish either commercially or recreationally on a trip-by-trip basis, applied an online contingent sequential stated choice approach to better understand the decision-making of this unique group (Chapter III). Responses indicated that, while some permit holders consistently fish either recreationally or commercially, a substantial proportion of participants change trip type depending on fishery conditions such as prevailing fish size or regulations. The changing behavior of this latter group could potentially result in large shifts in targeting and lead to overages for the commercial handgear sector or recreational sector, and potentially the U.S. bluefin tuna quota as a whole. Lastly, post-release mortality was estimated for juvenile bluefin tuna caught in the increasingly popular light-tackle recreational fishery while also beta testing a newly developed, solar-powered pop-up satellite archival tag designed to enable large-scale, high-precision mortality studies (Chapter IV). Data were only obtained for 15 of 22 deployed tags, with 14 fish demonstrating behavior consistent with survival. One fish was predated upon, likely by a shortfin mako shark, after 17 days, and this was considered a natural rather than a fishing mortality. The low level of estimated post-release mortality, consistent with results from previous studies on different size classes of bluefin tuna caught with various angling gear types, suggests that catch-and-release angling, which Chapter II showed to be highly valued by some anglers, is a viable conservation strategy. Overall, this dissertation provides information regarding both angler preferences and fishery impacts that are of direct relevance to management. Future efforts should be directed to further engaging the recreational bluefin tuna fishing community in order to improve buy-in to management strategies and improve the ability of the United States to maintain fishing mortality within internationally prescribed limits.